THURSDAY, Aug. 22 (HealthDay News) -- Before full-blown diabetes sets in, people typically develop a syndrome known as "prediabetes." Now a new study shows that people who are not obese but who have a family history of diabetes are at higher risk of becoming prediabetic, too.

Prediabetes is a condition where blood sugar levels are higher than normal, but not as high as seen in diabetes.

It was known that a family history of type 2 diabetes increases a person's risk of diabetes, but it was not known if it increased the risk of prediabetes.

In the study, researchers led by Dr. Andreas Fritsche of the German Center for Diabetes Research looked at more than 5,400 people with normal blood sugar levels and more than 2,600 with prediabetes.

After taking into account age, sex and body fat, the researchers concluded that people with a family history of diabetes were 26 percent more likely to develop prediabetes.

Further analysis showed that the link between a family history of diabetes and prediabetes risk was seen only in people who were not obese, according to the study which was published Aug. 21 in the journal Diabetologia.

One expert not connected to the study said the finding raises new questions.

"It is interesting to note that this association was not demonstrated in those who were obese," said Dr. Alyson Myers, an endocrinologist at North Shore University Hospital in Manhasset, N.Y. "It would be helpful to look at these patients over time -- rather than at one point in time as was done in this study -- to see how these rates would change with weight loss or gain."

The study authors offered up their own theory on why the connection was most evident among slimmer people. "This might indicate [that] the effect of family history on prediabetes becomes readily measurable only when not overshadowed by strong risk factors such as obesity," they wrote.